Method and system for treating oil field waste mud filter-pressing wastewater

Abstract

The invention relates to a method and system for treating oil field waste mud filter-press wastewater, and the method comprises the following steps: carrying out air flotation oil removal treatment on the oil field waste mud filter-press wastewater to obtain first wastewater; performing multi-stage anaerobic treatment on the first wastewater by using a biological enzyme carbon source to obtain second wastewater; performing multi-stage aerobic treatment on the second wastewater by using a bio-enzyme enhanced liquid to obtain third wastewater; carrying out first precipitation and rough filtration on the third wastewater; carrying out multi-metal catalytic oxidation reaction treatment on the roughly filtered third wastewater to obtain fourth wastewater; and carrying out secondary precipitation, adsorption and refined filtration on the fourth wastewater to obtain the oil field waste mud filter-pressing wastewater subjected to standard treatment. The final oil field waste mud filter-press wastewater which is treated by the method and reaches the standard meets the effluent COD (Chemical Oxygen Demand) of 40mg / L-50mg / L, the ammonia nitrogen of 0-2mg / L and the total nitrogen of 8mg / L-12mg / L.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a method and system for treating waste oilfield mud filter press wastewater. Background Technology

[0002] Drilling waste mud is one of the major pollutants in the petroleum industry. It is a mixed system containing clay, various chemicals, wastewater, and oil, and contains a large number of pollutants with varying toxicity and biodegradability. Currently, the common treatment method for drilling waste mud involves first coarse filtration through a vibrating screen to remove rock cuttings, then homogenizing the mud by adding different agents and stirring thoroughly to stabilize, coagulate, and aggregate the mud. Finally, a filter press is used to separate the destabilized mud into solid and liquid components, producing mud filter wastewater.

[0003] The organic additives in oilfield wastewater are diverse and complex, primarily consisting of high-molecular polymers and surfactants. These include weighting agents, clay stabilizers, corrosives, preservatives, bactericides, lubricants, formation affinity agents, defoamers, and heavy metals. Key characteristics include poor biodegradability and high salt content. The properties of oilfield wastewater vary across different oilfields, and even within the same region, different blocks exhibit significant differences in water quality. Currently, the main treatment technologies for oilfield wastewater from oilfield filtration include advanced oxidation processes, coagulation, anaerobic-aerobic processes, anaerobic-anoxic-aerobic processes, and ultrafiltration combined with reverse osmosis, but none have focused on biochemical degradation treatment. Summary of the Invention

[0004] This application provides a method and system for treating waste oilfield mud filter press wastewater to solve the following technical problem: providing a new method for treating waste oilfield mud filter press wastewater.

[0005] In a first aspect, this application provides a method for treating wastewater from oilfield waste mud pressure filtration, the method comprising:

[0006] The wastewater from oilfield mud filter press is treated with air flotation for oil removal to obtain the first wastewater.

[0007] The first wastewater was subjected to multi-stage anaerobic treatment using a biological enzyme carbon source to obtain the second wastewater.

[0008] The second wastewater was subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution to obtain the third wastewater.

[0009] The third wastewater is subjected to a first sedimentation and coarse filtration.

[0010] The coarsely filtered third wastewater is treated with a multi-metal catalytic oxidation reaction to obtain the fourth wastewater.

[0011] Optionally, the carbon source of the bioenzyme includes microbial enzyme preparations, glycerol, and sodium acetate.

[0012] Optionally, the carbon source of the bio-enzyme is 50 mg to 500 mg relative to 1 L of the first wastewater.

[0013] Optionally, the bio-enzyme-enhancing solution includes dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparations, and trace elements required by microorganisms.

[0014] Optionally, the amount of the bio-enzyme-enhancing solution is 30 mg to 100 mg relative to 1 L of the second wastewater.

[0015] Optionally, the step of using a bio-enzyme-enhanced solution to perform multi-stage aerobic treatment on the second wastewater to obtain the third wastewater includes:

[0016] The second wastewater was subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution and flexible porous gel packing material to obtain the third wastewater.

[0017] Optionally, the agents used in the air flotation oil removal treatment include: a net-catching agent, a flocculant, and a pH adjuster.

[0018] Optionally, relative to 1L of the oilfield waste mud filter press wastewater, the net trapping agent is 30mg to 300mg, the flocculant is 5mg to 30mg, and the pH adjuster is 50mg to 200mg.

[0019] Optionally, the method further includes: subjecting the fourth wastewater to a second sedimentation, adsorption, and fine filtration to obtain treated oilfield waste mud filter press wastewater that meets the standards.

[0020] Secondly, this application provides a system for treating waste oilfield mud filter press wastewater, used to implement the method described in any embodiment of the first aspect. The system includes: a nano-microbubble flotation device 1, a multi-stage anaerobic reactor 2, a multi-stage aerobic reactor 3, a first sedimentation tank 4, a multi-media coarse filter tank 5, a nano-multimetal catalytic reactor 6, a second sedimentation tank 7, an activated carbon microbial reactor 8, and a multi-media fine filter tank 9.

[0021] The technical solutions provided in this application have the following advantages compared with the prior art:

[0022] The method for treating waste oilfield mud filter press wastewater provided in this application includes: subjecting the waste oilfield mud filter press wastewater to air flotation for oil removal to obtain first wastewater; subjecting the first wastewater to multi-stage anaerobic treatment using a bio-enzyme carbon source to obtain second wastewater; subjecting the second wastewater to multi-stage aerobic treatment using a bio-enzyme enhanced solution to obtain third wastewater; subjecting the third wastewater to first sedimentation and coarse filtration; and subjecting the coarsely filtered third wastewater to a multi-metal catalytic oxidation reaction to obtain fourth wastewater. Oilfield waste mud filter press wastewater undergoes air flotation for oil removal, separating high-molecular flocculants, oily substances, and suspended solids (SS). Multi-stage anaerobic treatment of the first wastewater using bio-enzyme carbon sources promotes anaerobic sludge formation, ammoniation of organic nitrogen in the first wastewater, and improves its biodegradability. Multi-stage aerobic treatment of the second wastewater using bio-enzyme-enhanced liquid promotes the oxidative decomposition of recalcitrant organic pollutants by microorganisms and shields them from the toxicity of chemical residues, further degrading recalcitrant organic nitrogen and ammonia nitrogen into nitrate nitrogen. This multi-stage anaerobic-aerobic treatment ensures continuous and stable removal of COD, ammonia nitrogen, and total nitrogen from the wastewater. The third wastewater undergoes a first sedimentation process to separate sludge and wastewater. The wastewater after the first sedimentation is then coarsely filtered to remove residual suspended solids and colloidal substances. Finally, the coarsely filtered third wastewater undergoes metal-catalyzed oxidation to further remove remaining recalcitrant organic matter. In summary, the wastewater treatment agent system is a series of biological enzyme agents. By adjusting the proportion of nutrients in the water, it improves the treatment effect of activated sludge, reduces the load on the physicochemical treatment section, and lowers operating costs. Furthermore, it removes recalcitrant organic matter through multi-metal catalytic reactions, significantly reducing the concentration of organic matter in the effluent. This provides a new process combination method for the treatment of waste sludge filter press wastewater. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic flowchart illustrating a method for treating waste oilfield mud filter press wastewater, provided in an embodiment of this application;

[0026] Figure 2This application provides a schematic diagram of the structure of a system for treating waste oilfield mud filter press wastewater; wherein,

[0027] 1-Nano microbubble flotation device, 2-Multi-stage anaerobic reactor, 21-First-stage anaerobic reactor, 22-Second-stage anaerobic reactor, 3-Multi-stage aerobic reactor, 31-First-stage aerobic reactor, 32-Second-stage aerobic reactor, 4-First sedimentation tank, 5-Multi-media coarse filter tank, 6-Nano multi-metal catalytic reactor, 7-Second sedimentation tank, 8-Activated carbon microbial reactor, 9-Multi-media fine filter tank. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0030] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] Firstly, this application provides a method for treating wastewater from oilfield waste mud pressure filtration. Figure 1 Please refer to the flowchart illustrating a method for treating waste oilfield mud filter press wastewater provided in this application embodiment. Figure 1 The method includes:

[0033] S1. The wastewater from oilfield mud filter press is treated by air flotation to remove oil, resulting in the first wastewater.

[0034] In this embodiment, the oil removal treatment via flotation is specifically a nano-microbubble flotation treatment. Nano-microbubble flotation utilizes micro- and nano-bubbles to efficiently mix and dissolve air and liquid, generating a large number of micro- and nano-bubbles. These numerous tiny bubbles come into full contact with suspended solids in the water. Due to their large surface area, the micro- and nano-bubbles can adhere to a large number of suspended flocs in the water, which then float to the surface, forming scum. This scum is then scraped off, thus purifying the suspended impurities and fine oil in the water. When the micro- and nano-bubbles burst, they generate free radicals, breaking complex bonds and improving the biodegradability of wastewater while rapidly and efficiently removing odors. Nano-microbubble flotation does not require reflux water, has a compact equipment structure, and eliminates the need for air compressors and reflux pumps, resulting in significant energy savings. Because of the small particle size and high utilization rate of the microbubbles, the dosage can be reduced. Even with small flocs, bubble water can be formed and float to the surface. Furthermore, the nano-microbubble flotation equipment operates stably and with low noise.

[0035] In some embodiments, the agents used in the air flotation oil removal treatment include: a net-catching agent, a flocculant, and a pH adjuster.

[0036] In this embodiment, oilfield waste mud dewatering is treated by adding a scavenging agent, a flocculant, and a pH adjuster to separate high-molecular-weight flocs, oily substances, and suspended solids (SS). SS represents suspended solids, referring to solids suspended in water, including insoluble inorganic and organic matter, as well as mud, clay, and microorganisms. The scavenging agent's excellent adsorption characteristics and reactivity promote the dispersion of non-polymerizing micro-polymers, heavy metal colloids, and SS, forming dense and stable flocs. The flocculant's bridging effect enables the flocculation of SS and colloids. The pH adjuster controls the pH of the effluent from the air flotation oil removal treatment to 7.0–8.5. For example, the scavenging agent can be surface-modified nano-zero-valent iron coupled with nano-sized polyaluminum chloride, basic aluminum iron salt, etc.; the flocculant can be polyacrylamide (PAM), polysilicic acid, etc.; and the pH adjuster can be sodium carbonate, sodium hydroxide, etc.

[0037] In some embodiments, relative to 1L of the oilfield waste mud filter press wastewater, the net-catching agent is 30mg to 300mg, the flocculant is 5mg to 30mg, and the pH adjuster is 50mg to 200mg.

[0038] In the embodiments of this application, the dosage of the net-catching agent can be 30 mg / L to 300 mg / L, thereby causing the oilfield waste mud filter press wastewater to be flushed away and unable to repolymerize small polymers, heavy metals and other colloids and suspended solids, and to form dense and stable flocs; the dosage of the flocculant can be 5 mg / L to 30 mg / L, thereby promoting the formation of nano-microbubbles by the flocs and nitrogen to form scum; the dosage of the pH adjuster can be 50 mg / L to 200 mg / L, thereby adjusting the pH of the effluent from the air flotation oil removal treatment to meet the anaerobic influent conditions and reach pH 7.0 to 8.5. For example, relative to 1L of oilfield waste mud filter press wastewater, the net trap can be 30mg, 50mg, 70mg, 100mg, 150mg, 200mg, 250mg, 300mg, etc., the flocculant can be 5mg, 10mg, 15mg, 20mg, 25mg, 30mg, etc., and the pH adjuster can be 50mg, 80mg, 100mg, 130mg, 150mg, 170mg, 200mg, etc.

[0039] S2. The first wastewater is subjected to multi-stage anaerobic treatment using a biological enzyme carbon source to obtain the second wastewater;

[0040] In this embodiment, the bio-enzyme carbon source differs from traditional single carbon sources. It is mainly produced from raw materials such as biological nutrient solution, oxidase, and hydrolase through microbial catalytic sealed fermentation technology. The bio-enzyme carbon source can provide nutrients for microorganisms in the wastewater treatment process, while also providing the enzyme medium required for microorganisms to decompose and degrade organic matter, accelerating the biochemical reaction process. Through bio-enzyme catalysis, microorganisms break down large molecules and long carbon chain organic matter into alcohols, ethers, and sugars that are easily decomposed and absorbed by microorganisms, thus achieving efficient decomposition, degradation, absorption, and utilization of organic pollutants. Using the bio-enzyme carbon source to perform multi-stage anaerobic treatment on the first wastewater can effectively mix pollutants, microorganisms, and the bio-enzyme carbon source (which provides an energy source for bacteria in the microbial treatment system), promoting the formation of anaerobic microbial EPS (extracellular polymeric substances) and improving sludge shape, thereby promoting the formation of anaerobic sludge and improving sludge formation efficiency, ultimately promoting the ammoniation of organic nitrogen and the biodegradability of B / C in the first wastewater. Since the first wastewater contains a large amount of organic nitrogen, multi-stage anaerobic treatment is required to ensure the denitrification effect. In addition, the process parameters for the above-mentioned multi-stage anaerobic treatment include: anaerobic treatment time of 7 to 15 hours per stage, anaerobic temperature of 20°C to 35°C per stage, dissolved oxygen of 0 mg / L to 0.2 mg / L per stage, and ORP of -0.2V to +0.4V per stage.

[0041] In some embodiments, the carbon source of the bioenzyme includes microbial enzyme preparations, glycerol, and sodium acetate.

[0042] In some embodiments, the bio-enzyme carbon source is 50 mg to 500 mg relative to 1 L of the first wastewater.

[0043] In this embodiment, the bio-enzyme carbon source may include microbial enzyme preparations, glycerol, and sodium acetate. Anaerobic treatment, in addition to hydrolysis and acidification, can achieve synergistic metabolism of recalcitrant organic matter by adding a bio-enzyme carbon source, thereby increasing the activity and concentration of anaerobic sludge. Since waste sludge filter press wastewater has poor biodegradability and a low B / C ratio, biochemical removal of COD is difficult. By adding a bio-enzyme carbon source (50 mg / L to 500 mg / L), synergistic metabolism of recalcitrant COD can be achieved. During synergistic metabolism, microorganisms first proliferate by degrading and absorbing the bio-enzyme carbon source. After reaching a certain number and concentration, they then degrade recalcitrant COD substances through synergistic metabolism. For example, relative to 1 L of the first wastewater, the bio-enzyme carbon source can be 50 mg, 100 mg, 150 mg, 200 mg, 250 mg, 300 mg, 350 mg, 400 mg, 450 mg, or 500 mg.

[0044] S3. The second wastewater is subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution to obtain the third wastewater;

[0045] In the embodiments of this application, in the multi-stage aerobic treatment, a bio-enzyme enhancement solution is added. By adding the bio-enzyme enhancement solution, the ratio of organic matter and trace elements in the wastewater is adjusted to the optimal level, thereby enhancing the aerobic microbial treatment effect.

[0046] In some embodiments, the bio-enzyme-enhancing solution includes dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparations, and trace elements required by microorganisms.

[0047] In some embodiments, the bio-enzyme-enhancing solution is 30 mg to 100 mg relative to 1 L of the second wastewater.

[0048] In this embodiment, the bio-enzyme-enhancing solution may include dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparations, and trace elements required by microorganisms such as Fe and Mn. Besides the conventional elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur) required for microbial growth, the bio-enzyme-enhancing solution may also include trace elements such as calcium, potassium, magnesium, sulfur, selenium, zinc, boron, copper, vitamins, and growth factors. These trace elements participate in the composition of amino acids and enzymes in microorganisms, regulate the colloidal state of the protoplasm, maintain cell osmosis and balance, and also act as enzyme activators. By adding the bio-enzyme-enhancing solution to wastewater, the missing elements in the wastewater are replenished, thereby achieving healthy reproduction and growth of microorganisms. The dosage of the bio-enzyme-enhanced solution can be 30 mg / L to 100 mg / L. After mixing with nitrogen, enzymes, and organic carbon sources, the bio-enzyme-enhanced solution stimulates beneficial aerobic bacteria to decompose organic matter in wastewater, promotes microbial reproduction and EPS formation, enhances the microbial capacity for oxidative decomposition of pollutants, and shields against the toxicity of chemical residues to microorganisms. It further degrades recalcitrant organic matter and ammonia nitrogen in the water into nitrate nitrogen. However, due to the high total nitrogen and organic nitrogen content in the second wastewater, multi-stage aerobic treatment is required to ensure ammonification and nitrification effects. Furthermore, the process parameters for the aforementioned multi-stage aerobic treatment include: aerobic treatment time of 10 to 15 hours per stage, aerobic temperature of 20℃ to 35℃ per stage, dissolved oxygen of 2.0 mg / L to 4.0 mg / L per stage aerobic unit, and ORP of +0.2V to +0.5V per stage aerobic unit.

[0049] In some embodiments, the step of using a bio-enzyme-enhanced solution to perform multi-stage aerobic treatment on the second wastewater to obtain the third wastewater includes:

[0050] The second wastewater was subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution and flexible porous gel packing material to obtain the third wastewater.

[0051] In this embodiment, the flexible porous gel packing can be polyurethane packing or high-density polyethylene suspended carrier packing; the amount added can be 1 / 3 to 1 / 2 of the aerobic reactor volume. The flexible porous gel packing is in a fluidized state during aerobic treatment, thereby forming suspended activated sludge and attached biofilm.

[0052] S4. The third wastewater is subjected to first sedimentation and coarse filtration;

[0053] In this embodiment of the application, the third wastewater undergoes a first sedimentation process to separate the sludge and sewage in the third wastewater using physical methods. Then, a multi-media coarse filtration process is performed to remove the residual suspended solids and colloidal substances in the wastewater.

[0054] S5. The coarsely filtered third wastewater is subjected to a multi-metal catalytic oxidation reaction to obtain the fourth wastewater.

[0055] In this embodiment, the polymetallic catalytic oxidation reaction treatment specifically refers to the nano-polymetallic catalytic oxidation reaction treatment. Nano-polymetallic catalytic reaction technology is a novel oxidation technology belonging to advanced oxidation technologies. Besides possessing the advantages of traditional polymetallic catalytic reactions, such as rapid action and non-selectivity, this technology also exhibits higher activity, greatly contributing to the degradation of macromolecular organic matter and improving effluent water quality. Nano-polymetallic materials are a class of materials with a three-dimensional bicontinuous nanoporous structure, characterized by controllable size, good conductivity, low density, and high specific surface area. Nano-polymetallic catalytic materials possess characteristics such as high specific surface area, no loading, clean surface, high activity at low temperatures, ease of preparation, easy recovery, and easy reuse, giving them unique activity in the field of catalytic oxidation. Simultaneously, the three-dimensional bicontinuous porous structure of nano-polymetallic materials has been shown to favor the presence of high-density, low-coordination atoms, which are often the active centers of catalytic reactions. Nano-polymetallic catalysts have achieved highly efficient catalysis of a variety of important reactions, exhibiting high activity, selectivity, and stability in these reactions. This technology overcomes many shortcomings of traditional multi-metal catalytic materials, enhances the low-temperature catalytic oxidation effect, reduces the influence of temperature on catalytic oxidation, and can stably and effectively catalyze recalcitrant organic matter at room temperature. In particular, the nano-multi-metal catalytic materials can be reused, saving operating costs. Therefore, the third type of wastewater is treated by multi-metal catalytic oxidation to achieve hydrogen reduction of recalcitrant polymers, improving the B / C biodegradability of the wastewater and degrading recalcitrant organic matter. Furthermore, the nano-multi-metal materials can include: reduced iron powder, coking coal powder, Mn, and other metal oxides; the residence time of the packing layer can be 30-60 minutes. During the nano-multi-metal catalytic oxidation treatment, an acidic pH adjuster (sulfuric acid, hydrochloric acid) needs to be added to adjust the pH value required for the catalytic reaction, and the effluent pH value can be 5.5-6.5. For example, the main component of the multi-metal catalyst is a mixture of aluminum, zinc, magnesium, iron, carbon, and iron-carbon particles, with an addition amount of 100 mg / L-200 mg / L.

[0056] In some embodiments, the method further includes: S6, subjecting the fourth wastewater to a second sedimentation, adsorption, and fine filtration to obtain treated oilfield waste mud filter press wastewater that meets the standards.

[0057] In this embodiment, the wastewater treated by the nano-polymetallic catalytic reaction undergoes a second sedimentation, simultaneously using coagulation and sedimentation agents. These sedimentation agents include coagulants and coagulant aids. The coagulants can cause suspended solids (SS) and colloidal particles to react and aggregate into flocs. Coagulants include: entrapment agents, basic aluminum ferric sulfate, polyaluminum chloride (PAC), polyferric sulfate (PFS), etc., with a dosage of 20 mg / L to 120 mg / L, thereby causing SS and colloids to aggregate into flocs. The coagulant aids can promote floc formation through bridging and entrapment by polymeric coagulant aids. Coagulant aids include: PAM, polymeric modified starch flocculants, polymeric silicate flocculants, etc., with a dosage of 5 mg / L to 50 mg / L. Therefore, the synergistic effect of the flocculants and coagulant aids enables the aggregation and bridging of SS and colloids into flocs, achieving rapid sedimentation.

[0058] After the second sedimentation treatment, the wastewater undergoes sequential activated carbon microbial adsorption and multi-media fine filtration to finally meet the treatment requirements. Specifically, adsorption involves using coal-based granular activated carbon to adsorb large-scale, recalcitrant wastewater via van der Waals forces. A biofilm and polysaccharide biocatalyst form within the activated carbon adsorption channels, biocatalyzing the degradation of organic matter in the activated carbon adsorption channels, restoring the van der Waals forces of the activated carbon, and improving its adsorption efficiency. The biofilm degrades organic nitrogen and ammonia nitrogen into nitrogen gas, achieving the purpose of decarbonization and nitrogen removal. Multi-media fine filtration ensures that the effluent SS meets discharge standards, while advanced treatment ensures continuous and stable removal of COD, ammonia nitrogen, and total nitrogen from the fourth wastewater.

[0059] Ultimately, the treated wastewater meets the following standards: COD 40-50 mg / L, ammonia nitrogen 0-2 mg / L, and total nitrogen 8-12 mg / L, satisfying the Class A discharge standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" GB18918-2002. This method is applicable to sludge filtrate with a pH of 5-7, COD of 1348-2890 mg / L, ammonia nitrogen of 17.9-21 mg / L, total nitrogen of 21-29 mg / L, total phosphorus of 11-17.9 mg / L, and total salt of 9800-15000 mg / L.

[0060] Secondly, this application provides a system for treating waste oilfield mud filter press wastewater, used to implement the method described in any embodiment of the first aspect. The system includes: a nano-microbubble flotation device 1, a multi-stage anaerobic reactor 2, a multi-stage aerobic reactor 3, a first sedimentation tank 4, a multi-media coarse filter tank 5, a nano-multimetal catalytic reactor 6, a second sedimentation tank 7, an activated carbon microbial reactor 8, and a multi-media fine filter tank 9.

[0061] In this embodiment, the water-based mud filtrate is homogenized and uniformly distributed before entering a nano-microbubble flotation device 1. The nano-microbubble flotation device 1 is connected to a multi-stage anaerobic reactor 2, which is connected to a multi-stage aerobic reactor 3. The multi-stage aerobic reactor 3 is connected to a sedimentation tank 4, which is connected to a multi-media coarse filter tank 5. The multi-media coarse filter tank 5 is connected to a nano-multimetal catalytic reactor 6, which is connected to a high-efficiency sedimentation tank 7. The high-efficiency sedimentation tank 7 is connected to an activated carbon microbial reactor 8, and the activated carbon microbial reactor 8 is connected to a multi-media fine filter tank 9.

[0062] The multi-stage anaerobic reactor 2 can be a two-stage anaerobic reactor connected in series. The first-stage anaerobic reactor 21 receives water from the top and is connected to the second-stage anaerobic reactor 22 at the bottom. The second-stage anaerobic reactor 22 receives water from the top. Both stages of anaerobic reactor 2 are equipped with independent internal reflux, with a reflux ratio of 100%. A biological enzyme carbon source is added at the inlet of the first-stage anaerobic reactor 21. The sedimentation tank 4 is connected to the first-stage anaerobic reactor 21, and the first-stage anaerobic reactor 21 is connected to the nano-microbubble flotation device 1.

[0063] The multi-stage aerobic reactor 3 can be a two-stage aerobic reactor connected in series. The first-stage aerobic reactor 31 is fed into the water from the top and connected to the second-stage aerobic reactor 32 in series from the bottom. The second-stage aerobic reactor 32 is discharged from the top. A biological enzyme enhancement solution is added to the inlet of the first-stage aerobic reactor 31. The second-stage aerobic reactor 32 is connected to the first sedimentation tank 4. Figure 2 A schematic diagram of a system for treating waste oilfield mud filter press wastewater provided in this application embodiment; please refer to... Figure 2 Wastewater from oilfield waste mud filtration is pumped to a nano-microbubble flotation oil removal unit 1, along with a dosing device for filtrate traps, flocculants, and pH adjusters. The wastewater undergoes pretreatment for oil and slag removal within the flotation unit. The flotation process utilizes a dissolved air pump with a unique nozzle design to create a high-speed vortex between water and air. Under high pressure, nitrogen in the air is cut and compressed into tiny bubbles, while oxygen is injected into the water at extremely high linear velocity. This generates highly mobile and efficient reactive oxygen species—hydroxyl radicals. These reactive oxygen species—hydroxyl radicals—rapidly pre-oxidize water pollutants, promoting the formation of dense and stable flocs that, together with nitrogen, encapsulate the nitrogen in nano-microbubbles to form scum. A scum scraper then separates the solid and liquid components, separating high-molecular-weight flocs, oil, and suspended solids (SS) from the wastewater. The chemical sludge generated at the bottom of the flotation unit 1 is directly transferred to the mud filtration section for filtration treatment along with the waste mud.

[0064] Wastewater treated by the nano-microbubble flotation oil removal device 1 is pumped into the multi-stage anaerobic reactor 2. The multi-stage anaerobic reactor 2 is equipped with a homogenizing water distribution device and an internal circulating water pump. At the same time, it is equipped with a biological enzyme carbon source dosing device to continuously add biological enzyme carbon source to the first-stage anaerobic reactor 21 of the multi-stage anaerobic reactor 2. By adding biological enzyme carbon source, the activity and concentration of anaerobic sludge are improved, and the synergistic metabolism of recalcitrant organic matter is achieved, which is then treated in conjunction with the second-stage anaerobic reactor 22.

[0065] After treatment in the multi-stage anaerobic reactor 22, the wastewater enters the multi-stage aerobic reactor 3 to remove biodegradable dissolved and colloidal organic pollutants. Flexible porous gel packing is installed in the aerobic reactor to enhance the treatment effect. At the same time, a bio-enzyme enhancement liquid dosing device is provided to add bio-enzyme enhancement liquid to the first-stage aerobic reactor 31 in the multi-stage aerobic reactor 3. By adding bio-enzyme enhancement liquid, the ratio of organic matter and trace elements in the wastewater is adjusted to the optimal level to enhance the aerobic microbial treatment effect and to treat the wastewater in synergistically with the second-stage aerobic reactor 32.

[0066] Wastewater treated by multi-stage aerobic reactor 32 enters the first sedimentation tank 4, where sludge and sewage are separated by physical methods. The sludge at the bottom of the first sedimentation tank 4 is continuously returned to the front-end multi-stage anaerobic reactor 2 to replenish sludge, while the remaining sludge enters the sludge dewatering device for volume reduction and harmless treatment.

[0067] The wastewater treated in the first sedimentation tank 4 enters the multi-media coarse filter tank 5, where residual suspended solids and colloidal substances in the wastewater are removed by secondary filtration. The multi-media coarse filter tank 5 is backwashed periodically.

[0068] The wastewater treated by the multi-media coarse filter tank 5 enters the nano-polymetallic catalytic reactor 6. At the same time, a sulfuric acid dosing device is used to add pH adjuster to the nano-polymetallic catalytic reactor 6 to adjust the appropriate pH value required for the catalytic reaction. The remaining recalcitrant organic matter in the wastewater undergoes catalytic oxidation reaction in the nano-polymetallic catalytic reactor 6.

[0069] Wastewater treated by the nano-polymetallic catalytic reactor 6 enters the second sedimentation tank 7 for physical sedimentation. At the same time, a coagulation and sedimentation agent dosing device is provided to add coagulant and coagulant aid to the front end of the second sedimentation tank 7.

[0070] The wastewater treated in the second sedimentation tank 7 is then sequentially treated in the activated carbon microbial reactor 8 and the multi-media fine filter tank 9 to finally meet the treatment requirements. The chemical sludge generated at the bottom of the second sedimentation tank is directly transferred to the sludge dewatering section for dewatering treatment together with the waste sludge.

[0071] Therefore, a combined treatment process of "nano-microbubble flotation device + multi-stage anaerobic reactor + multi-stage aerobic reactor + first sedimentation tank + multi-media coarse filter tank + nano-multimetal catalytic reactor + second sedimentation tank + activated carbon microbial reactor + multi-media fine filter tank" is adopted. For waste sludge filter press wastewater with different water quality, a series of biological enzymes of different concentrations and proportions are added to the biological system to ensure that the treated wastewater consistently meets the standards. This solves the practical problems of low sludge concentration, poor biochemical degradation capacity, weak microbial salt tolerance, poor system resistance to shock loads, high operating costs, and unstable effluent quality in the current waste sludge filter press wastewater treatment system.

[0072] The system for treating waste oilfield mud filter press wastewater is based on the above-described method for treating waste oilfield mud filter press wastewater. The specific steps of the method for treating waste oilfield mud filter press wastewater can be referred to the above embodiments. Since the system for treating waste oilfield mud filter press wastewater adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0073] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0074] Example 1

[0075] A mud treatment plant of Liaohe Oilfield Environmental Engineering Company in Panjin has an annual processing capacity of 80,000 m³ of waste water-based mud. 3 The treated mud filtrate had an average pH of 6.5, an average COD of 2460 mg / L, an average ammonia nitrogen of 19.8 mg / L, an average total nitrogen of 26.3 mg / L, an average total phosphorus of 14.2 mg / L, and an average total salt of 12620 mg / L.

[0076] A method for treating wastewater from oilfield mud dewatering includes:

[0077] S11. The wastewater from oilfield mud filter press is treated by air flotation to remove oil, resulting in the first wastewater. The reagents used in the air flotation oil removal treatment include: a net trap, a flocculant, and a pH adjuster. The main component of the net trap is high-efficiency compounded polyaluminum chloride, with an addition amount of 120 mg / L. The flocculant is anionic polyacrylamide, with an addition amount of 20 mg / L. The pH adjuster is sodium carbonate, with an addition amount of 100 mg / L.

[0078] S21. The first wastewater is subjected to multi-stage anaerobic treatment (two stages) using a bio-enzyme carbon source to obtain the second wastewater; wherein, the bio-enzyme carbon source includes microbial enzyme preparation, glycerol, and sodium acetate, and the concentration of the bio-enzyme carbon source is 50 mg / L; the total time of the two-stage anaerobic treatment is 16 hours, the temperature of each stage of anaerobic treatment is 27℃, the dissolved oxygen of each stage of anaerobic treatment is below 0.1 mg / L, and the ORP of each stage of anaerobic treatment is 0.05V;

[0079] S31. The second wastewater is subjected to multi-stage aerobic treatment (two stages) using a bio-enzyme-enhanced solution to obtain the third wastewater. The bio-enzyme-enhanced solution includes dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparation, and trace elements required by microorganisms. The concentration of the bio-enzyme-enhanced solution is 80 mg / L. The total time for the two-stage aerobic treatment is 20 hours. The temperature of each aerobic stage is 26-27℃. The dissolved oxygen in each aerobic stage is 2-2.5 mg / L. The ORP of each aerobic stage is between +0.2 and +0.30V.

[0080] S41. The third wastewater is subjected to first sedimentation and coarse filtration;

[0081] S51. The coarsely filtered third wastewater is subjected to a multi-metal catalytic oxidation reaction to obtain fourth wastewater; wherein, the pH value of the coarsely filtered third wastewater is 4.0-5.0, and the main component of the multi-metal catalyst is a mixture composed of aluminum, zinc, magnesium, iron, carbon and iron-carbon particles; the dosage is 100 mg / L.

[0082] S61. The fourth wastewater undergoes a second sedimentation, adsorption, and fine filtration to obtain treated oilfield waste mud filter press wastewater that meets the standards. The pH of the fourth wastewater is adjusted to 7.5-8. Suspended solids in the water are removed by adding 100 mg / L of polyaluminum chloride and 20 mg / L of anionic polyacrylamide. Then, the adsorption capacity of activated carbon and the COD treatment capacity of specific microorganisms growing on the surface of activated carbon are utilized to remove the remaining adsorbable and degradable COD in the water. Finally, the finely filtered effluent meets the standards for discharge.

[0083] Example 1 data: Average effluent quality over 60 days: pH 7.4, COD 43 mg / L, ammonia nitrogen 1.4 mg / L, total nitrogen 11.3 mg / L, total phosphorus 0.3 mg / L, meeting the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" GB18918-2002. CODcr, TP, and NH3-N were monitored online every two hours, while TN was tested weekly using the national laboratory standard method.

[0084] Example 2

[0085] The Shuguang mud treatment station of Liaoning Oilfield Environmental Engineering Company has an annual processing capacity of 120,000 m³ of waste water-based mud. 3The treated mud filtrate had an average pH of 6.2, an average COD of 1940 mg / L, an average ammonia nitrogen of 23.2 mg / L, an average total nitrogen of 28 mg / L, an average total phosphorus of 11.2 mg / L, and an average total salt of 9840 mg / L.

[0086] A method for treating wastewater from oilfield mud dewatering includes:

[0087] S12. The wastewater from oilfield mud filter press is treated by air flotation to remove oil, resulting in the first wastewater. The reagents used in the air flotation oil removal treatment include: a net trap, a flocculant, and a pH adjuster. The main component of the net trap is high-efficiency compounded polyaluminum chloride, with an addition amount of 90 mg / L. The flocculant is anionic polyacrylamide, with an addition amount of 15 mg / L. The pH adjuster is sodium carbonate, with an addition amount of 70 mg / L.

[0088] S22. The first wastewater is subjected to multi-stage anaerobic treatment (three stages) using a biological enzyme carbon source to obtain the second wastewater; wherein, the biological enzyme carbon source includes microbial enzyme preparation, glycerol, and sodium acetate, and the concentration of the biological enzyme carbon source is 40 mg / L; the total time of the three-stage anaerobic treatment is 24 hours, the temperature of each stage of anaerobic treatment is 30℃, the dissolved oxygen of each stage of anaerobic treatment is below 0.1 mg / L, and the ORP of each stage of anaerobic treatment is 0.14V;

[0089] S32. The second wastewater is subjected to multi-stage aerobic treatment (two stages) using a bio-enzyme-enhanced solution to obtain the third wastewater. The bio-enzyme-enhanced solution includes dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparation, and trace elements required by microorganisms. The concentration of the bio-enzyme-enhanced solution is 50 mg / L. The total time for the two-stage aerobic treatment is 24 hours. The temperature of each aerobic stage is 25-27℃. The dissolved oxygen in each aerobic stage is 4 mg / L. The ORP of each aerobic stage is between +0.25 and +0.40V.

[0090] S42. The third wastewater is subjected to first sedimentation and coarse filtration;

[0091] S52. The coarsely filtered third wastewater is subjected to a multi-metal catalytic oxidation reaction to obtain fourth wastewater; wherein, the pH value of the coarsely filtered third wastewater is 4.0-4.5, and the main component of the multi-metal catalyst is a mixture composed of aluminum, zinc, magnesium, iron, carbon and iron-carbon particles; the dosage is 150 mg / L.

[0092] S62. The fourth wastewater undergoes a second sedimentation, adsorption, and fine filtration to obtain treated oilfield waste mud filter press wastewater that meets the standards. The pH of the fourth wastewater is adjusted to 7.5-8. Suspended solids in the water are removed by adding 80 mg / L of polyaluminum chloride and 15 mg / L of anionic polyacrylamide. Then, the adsorption capacity of activated carbon and the COD treatment capacity of specific microorganisms growing on the surface of activated carbon are utilized to remove the remaining adsorbable and degradable COD in the water. Finally, the finely filtered effluent meets the standards for discharge.

[0093] Example 2 data: Average effluent quality over 300 days: pH 7.2, COD 39 mg / L, ammonia nitrogen 1.7 mg / L, total nitrogen 10.2 mg / L, total phosphorus 0.25 mg / L, meeting the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants".

[0094] The Class A standard in GB18918-2002. CODcr, TP, NH3-N, and TN are all monitored online with data output every 3 hours, and all tests are conducted daily using the national laboratory standard method.

[0095] It should be noted that the above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for treating wastewater from oilfield mud pressure filtration, characterized in that, The method includes: The wastewater from oilfield mud filter press is treated with air flotation for oil removal to obtain the first wastewater. The first wastewater was subjected to multi-stage anaerobic treatment using a biological enzyme carbon source to obtain the second wastewater. The second wastewater was subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution to obtain the third wastewater. The third wastewater is subjected to a first sedimentation and coarse filtration. The coarsely filtered third wastewater is treated with a multi-metal catalytic oxidation reaction to obtain the fourth wastewater.

2. The method according to claim 1, characterized in that, The carbon source of the bio-enzyme includes microbial enzyme preparations, glycerol, and sodium acetate.

3. The method according to claim 2, characterized in that, The carbon source of the bio-enzyme is 50 mg to 500 mg relative to 1 L of the first wastewater.

4. The method according to claim 1, characterized in that, The bio-enzyme-enhancing solution includes dipotassium hydrogen phosphate, ammonium sulfate, microbial enzyme preparations, and trace elements required by microorganisms.

5. The method according to claim 4, characterized in that, The amount of the bio-enzyme-enhanced solution is 30 mg to 100 mg relative to 1 L of the second wastewater.

6. The method according to claim 1, characterized in that, The second wastewater is subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution to obtain the third wastewater, which includes: The second wastewater was subjected to multi-stage aerobic treatment using a bio-enzyme-enhanced solution and flexible porous gel packing material to obtain the third wastewater.

7. The method according to claim 1, characterized in that, The agents used in the air flotation oil removal treatment include: netting agent, flocculant and pH adjuster.

8. The method according to claim 7, characterized in that, Relative to 1L of the oilfield waste mud filter press wastewater, the net trapping agent is 30mg to 300mg, the flocculant is 5mg to 30mg, and the pH adjuster is 50mg to 200mg.

9. The method according to claim 1, characterized in that, The method further includes: The fourth wastewater is subjected to a second sedimentation, adsorption, and fine filtration to obtain treated oilfield waste mud filter press wastewater that meets the standards.

10. A system for treating wastewater from oilfield mud pressure filtration, characterized in that, For implementing the method according to any one of claims 1 to 9, the system comprises: a nano-microbubble flotation device (1), a multi-stage anaerobic reactor (2), a multi-stage aerobic reactor (3), a first sedimentation tank (4), a multi-media coarse filter tank (5), a nano-multimetal catalytic reactor (6), a second sedimentation tank (7), an activated carbon microbial reactor (8), and a multi-media fine filter tank (9).

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